The present invention relates to the method of making a tool to be used for hot-shaping of steel and other heavy metals; and more particularly, the invention relates to the making of a tool in a configuration of a compound construction part, including several metallical shapes and components, including, in particular, a basic tool or carrier element and a wear-resistant component, in a composite configuration.
Metallic compound parts, wherein two or more components of different materials are used but which are inseparately secured to each other, are known in many configurations. Usually, one provides a basic body or carrier and adds layers or lamina thereto, these additions being made of a material that depends upon the ultimate use of the particular part so made; the same, of course, is true with regard to the basic boy. The layering or depositing of the supplementary material could be carried out through galvanizing, welding, cladding, plating, or sintering of a metal powder upon the metallic, basic carrier body, usually consisting of a different material. Such a compound element is, for example, described in German printed patent application No. 17 58 162.
Powder metallurgy is a well-developed field of art; and herein, it is known to make compound parts. For example, a porous, powder-made skeleton is impregnated with a liquified component, such as copper, which will, of course, solidify inside the pores of the steel powder skeleton.
The methods described above are, however, limited to the making of compound parts which are relatively simple as far as their overall configuration is concerned. Complex shapes wherein for example the surface in a certain area or in several zones are to be made from a different material under exclusion of for example other surface parts cannot be made by any of the methods described above or not at least without great difficulties and certainly not in the general case. In other words, the afore-mentioned methods are restricted in their application with regard to the surface contour of the basic part!
A particular compound part which is desired to be made is, for example, a tool that is to be used in the hot-deforming and shaping of steel. Such a tool has certain zones which are to be provided with particular and especially wear- and ablation-proof material. Such a wear zone needs to be provided particularly in the case of hot-shaping tools; but it is believed that, heretofore, no adequate method does exist for making such a tool. A particular tool of interest is, for example, the billet guide in oblique rolling mills provided for making and working seamless steel pipes.
It is known generally that parts made on the basis of powder metallurgy and including particularly steel, nickel, or cobalt alloy powders, are highly resistive to wear. This resistiveness becomes particularly noticeable if such a part is used in heat-shaping and forming of steel. For example in the journal "Powder Metallurgy", Third European P. M. Symposium 1971, Conference Supplment Part 1, pp. 193-208, has been described a die for the extrusion of steel which, of course, is an element that will be subjected to wear in a rather extreme manner. The paper suggests here to construct such a die from a chrome nickel steel powder and make it by means of powder metallurgy. Such a ring is to be mounted in a forged holder. The compound state is obtained by shrinking the ring into the holding ring. It can be seen, however, that, in the case of large and/or complexly shaped hot-working tools, such an approach may be very difficult; and maybe, they are even too difficult to make and, most certainly, quite expensive. This is particularly true with regard to the making of a tool of complex configuration, and to making it in its entirety powder metallurgically under utilization of a processed steel alloy powder.
Billet or rolling stock guiding equipments have not been constructed in their entirety from powder, but as compound parts including, in each instance, a basic element, carrier, or component, and including further powder-metallurgically-made additions for the critical portions that are subjected to a high degree of wear. For this purpose, the basic body or component and the wear-resisting additions and supplementary components are mechanically worked and finished and joined by means of bolts. It can readily be seen that this procedure requires generally a rather extensive effort of matching and fitting until highly accurately matching surfaces for mutual engagement have been obtained.